The original Mirrycle (I could never understand why people couldn't realize it's pronounced "miracle" when they persist in calling it "mirri-cycle") works very well, but it's limited to use on conventional brake levers and, depending on the lever style, requires the gum hood on that side to be cut. This was not a dealbreaker back when those gum hoods were available in every bike shop. I've never mounted one on a lever that required drilling but would not hesitate to do so if it does not compromise the lever.

Don't tighten the little Allen bolts too much; if the pieces can't move easily when jostled (and this'll happen on tour) the plastic portions surrounding the nut inserts will crack. I've repaired more than one cracked stalk with a tiny hose clamp to help maintain the tension so the pieces don't swivel loosely.